Help stop spread of Manchurian wild rice, landowners urged

Landowners are being urged to report any sightings of one of Northland’s worst plant pests – Manchurian wild rice - and help stop its spread by cleaning and checking farm machinery.
Manchurian wild rice at Dargaville.

The Northland Regional Council, with funding from MAF, is more than three years into a lengthy battle against Manchurian wild rice which overruns pasture, threatens native species and chokes waterways.

The campaign against the highly invasive plant is making good headway, but landowners are vital to halting its spread and minimising costs to the region says the regional council’s project officer Curtis Harris.

“The most common way for this nasty weed to spread is in clumps of seed-contaminated dirt stuck to diggers and farm machinery.

Mr Harris says the pest is typically seen in the Kaipara district - where it has been an issue for many years - but authorities are especially keen to prevent it spreading to other, uninfested parts of the region.

“Simply checking and cleaning your machinery before using it elsewhere prevents Manchurian wild rice from being dragged into new parts of Northland.”

Mr Harris is also appealing to people to keep an eye out for the invasive plant which grows two to five metres high and quickly forms dense, choking stands.

Manchurian wild rice looks similar to raupo, and is often tucked away in old boggy areas or ditches. Any sightings should be reported to the council’s biosecurity team on 0800 002 004.

“The more eyes we have out there looking for it, the better – so if you suspect you have this pest on your land or along a waterway, please let us know,” says Mr Harris.

About $300,000 a year goes into Northland’s battle against Manchurian wild rice. The campaign is designed to halt the plant’s spread then steadily reduce its impact in the region. More than 300 sites throughout Northland are now being targeted.

Alongside the business-as-usual spraying that is a big part of the campaign, Mr Harris says they are also testing different ways to control the pest plant.

“There’s really no single silver bullet for dealing with this weed, so we’re trying to build up a range of effective tools for controlling it in different situations.”

The council is currently working with NIWA to trial the use of different vegetation along affected waterways, to stop Manchurian wild rice from re-establishing and prevent riverbank erosion after it is eradicated.

For areas where pest plants have invaded pasture, a wick-wiper applicator is being trialled. The wick-wiper boom brushes herbicide over the taller Manchurian wild rice plants, leaving pasture species below unaffected.

Both trials are in early stages, with results expected to be reported later this year.